Computer systems (e.g., desktops, laptops, servers, workstations, PDAs, etc.) generally comprise a plurality of components, such as memory, a display, a modem, a processor and/or a controller unit, which are integrated for a particular application. The components communicate through a bus, or collection of conductors, which comprises an address bus for identifying the components and a data bus for transferring data between the components. Moreover, computer systems often have multiple bus types, such as a local bus and an expansion bus (e.g., for add on components), each having an address and data bus. Computer systems also comprise many different bus architectures, such as ISA/AT (Industry Standard Architecture), EISA (Extended ISA), PCI (Peripheral Component Interconnect), VESA, and USB (Universal Serial Bus), which may have substantially different data transfer characteristics (e.g., clock speed and data bandwidth). Clock speed refers to the speed at which data is transferred, while data bandwidth refers to the amount of data that is transferred per transmittal. A local bus (e.g., PCI) connects almost directly to the processor, providing very fast throughput versus an expansion bus (e.g., AT). For example, an AT bus may run at 8 megahertz with a 16-bit bandwidth, while a PCI bus may operate at 33 or 66 megahertz with a 64-bit bandwidth.
Controllers utilize the buses and control the transfer of data among components of the computer system. For many devices, the local bus is desirable to ensure sufficient data transfer speed and bandwidth. Unfortunately, the components often outnumber the available controllers due to various cost restraints, space limitations, and other considerations. For example, an ASIC chipset (Application Specific Integrated Circuit) often has 2 host controllers for 4 or 6 ports and/or devices.
As mentioned above, the buses and controllers have limited data transfer capacities (i.e., speeds and bandwidths), which may depend on the particular architecture of the computer system. In contrast, devices have widely varying data transfer requirements, which may be substantially more demanding for some devices. For example, devices such as digital cameras and DVD-ROM drives typically require greater bandwidth than devices such as keyboards or pointer devices. A camera may require 70–80% of the available bandwidth, whereas a keyboard or mouse may require only 5–10% bandwidth. If two cameras are connected to a single controller, there may be a bottleneck if the controller does not have enough bandwidth for both of the cameras. Accordingly, the bottleneck may cause system or device failures, conflicts and/or other performance problems.
Currently, bandwidth utilization is maximized by intelligently attaching devices to the controllers. In many computer systems, the controllers are hardwired to a predetermined number of devices or ports (internal or external), preventing any reconfiguration other than by rearranging the devices. Accordingly, configuring the devices and components requires uncommon knowledge of board/chip design and device requirements, as well as time for the configuration. As computer technology continues to advance, computer systems are often upgraded by adding or replacing components. For example, a DVD-ROM drive or a digital camera may be added to an existing computer system. Unfortunately, a consumer generally lacks the computer expertise (e.g., system configurations, controller specifications, or device requirements) necessary to properly configure the devices to ensure sufficient data transfer rates for each of the devices. The typical consumer would tend to connect a newly purchased device to the first available port. Although this configuration may operate, it can cause device conflicts and/or performance problems if the connection results in insufficient bandwidth for one or more of the devices coupled to the port.
One solution would be to add more host controllers, or a dedicated controller for high speed devices. However, adding controllers results in higher costs for the computer system. As consumers continue to demand lower priced computer systems, it is desirable to keep the number of components and costs to a minimum. Furthermore, additional host controllers would not completely solve the problem, because each of the host controllers still has a limited amount of bandwidth for multiple devices.
Accordingly, there is a need for an improved technique for routing devices to host controllers to ensure that each device receives sufficient bandwidth and that each controller is not overloaded beyond its available bandwidth. It would be advantageous to provide a technique that would detect the bandwidth requirements for the devices, compare the bandwidth requirements with the available bandwidths from each of the controllers, and then distribute the devices to the controllers such that each device receives a desired bandwidth.